The invention relates to a gasket for sealing between opposed mating surfaces of two or more members adapted to be forcibly mated together and to clamp the sealing gasket therebetween. More particularly, in a preferred form, the invention relates to such gaskets preferably having a single-layer carrier with unique embossments and a flexible stopper portion.
Conventional gaskets, such as those used to seal between a cylinder head and cylinder block of an internal combustion engine, include two or more carrier members, such as those composed of spring steel, having various embossments to achieve proper sealing as well as the recovery needed to accommodate dynamic lifting of the cylinder head or other relative movement between the head and block. Such gaskets frequently include a stopper, which is an additional thin strip of metal or other material having a high stiffness. The stopper is located adjacent or near the combustion opening of the gasket in order to distribute sufficient load around the combustion opening area to properly seal and to prevent over-compression of adjacent combustion sealing embossments. In such constructions, the stopper is typically welded onto the carrier or formed from a folded-over portion of the carrier around the circumference of the combustion opening. In these designs, the stopper acts as the primary seal, with one or more other embossments acting as a secondary seal.
Although performing relatively well, such prior art constructions often suffer from certain disadvantages caused by the high rigidity of the stopper, such as high bore distortion, cylinder liner recessing, and inadequate accommodation of dynamic head lifting. Such disadvantages are frequently aggravated by the location of such highly rigid stoppers at or closely adjacent the combustion opening of the gasket, the cylinder head and the cylinder block.
In order to improve upon such gasket designs and to address the disadvantages of gaskets of the type discussed above, as well as others, the present invention seeks to reduce bore distortion, to reduce liner recession, and to accommodate greater dynamic head lifting while more evenly distributing loads circumferentially about the combustion opening. In addition, since the preferred form of a gasket according to the invention has a lower-cost single layer carrier, it significantly reduces load loss resulting from the greater amount of creep caused by multiple layer constructions, as well as eliminating misalignment between multiple layers, tolerance stack up among multiple layers and associated load variations. A preferred form of the inventive gasket allows for carrier embossments that are preselected to have a desired relative flexibility, that provides greater capability to follow relative motion between the members being sealed, and that increases the gasket's ability to accommodate rough mating surfaces of the members over that of prior art multiple layer gaskets. It should be noted that gaskets constructed according to the present invention are applicable in a variety of cylinder head and cylinder block applications, such as those found in internal combustion engines or gas compressors, for example, as well as in intake or exhaust manifold sealing, fuel cell component sealing and numerous other automotive or non-automotive industrial applications.
The present invention provides an improved gasket for sealing between opposed mating surfaces of two or more members having openings therein and that are adapted to be forcibly mated together, continuously or at least intermittently, to clamp the gasket therebetween, thus sealing around such openings, which are laterally aligned for longitudinal communication with each other. A gasket according to the present invention includes a carrier having first and second laterally extending sides or surfaces defining a longitudinal thickness therebetween. The carrier includes a gasket opening (as well as other coolant, lubricant, fastener or other openings, as required in a given application), with the gasket opening being adapted to be laterally aligned in longitudinal communication with the openings in the mating surface of the members when the gasket is clamped between the mated members. The preferred carrier is resiliently flexible in the longitudinal direction, but is relatively rigid in comparison to other elements of the gasket. A resilient sealing material that is substantially more flexible than the carrier material is disposed on at least portions of the laterally extending sides of the carrier for sealingly engaging the mated surfaces of the members at least adjacent their openings when the gasket is clamped between the mated members.
The carrier preferably includes a longitudinally flexible inner sealing portion disposed laterally adjacent the gasket opening with the inner sealing portion being longitudinally offset relative to the remainder of said carrier portion (or relative to an intermediate carrier portion located laterally outward of the inner sealing portion). The inner sealing portion is preferably offset in a longitudinal direction toward a first of the mating surfaces of the members when the gasket is being clamped therebetween and can be formed by way of embossing the relatively rigid (but still resiliently flexible) carrier, as well as by way of other forming methods or devices known to those skilled in the art. The inner sealing portion preferably includes the above-mentioned resilient sealing material disposed on at least portions of its laterally-extending sides for sealing engagement with the mating surfaces of the members when the gasket is clamped therebetween. These carrier features can be formed as embossments, for example, either before or after application of the resilient sealing material.
The preferred carrier also includes a longitudinally flexible stopper portion spaced laterally outwardly, away from the gasket opening so that the inner sealing portion and the flexible stopper portion are on opposite lateral sides of the above-mentioned the intermediate portion, or at least so that the flexible stopper portion is laterally outward relative to the inner sealing portion (i.e., with or without the intermediate carrier portion). The preferred flexible stopper portion is longitudinally convex relative to the remainder of the carrier (or relative to the intermediate carrier portion) on a side of the flexible stopper oriented toward one of the mating surfaces and is longitudinally concave relative to the remainder of the carrier (or relative to the intermediate carrier portion) on an opposite side of the flexible stopper oriented toward another of the mating surfaces of the members. The stopper, which can have a generally trapezoidal shape, for example, thus flexibly and resiliently limits the amount of longitudinal compression of the inner sealing portion but is typically less flexible than the inner sealing portion. The inner sealing portion is thus maintained in sealing engagement with the mating surfaces of both of the members during any relative movement therebetween when the members are mated together.
In a preferred form of the invention, the inner sealing portion is longitudinally offset to an extent greater than the extent of the longitudinal convexity of the flexible stopper so as to assure deflection of the inner sealing portion prior to compression of the flexible stopper. In addition, the resilient sealing material is preferably disposed within, and can completely fill or at least partially fill the concave side of the flexible stopper member. In specific applications, however, it may be satisfactory to optionally omit the resilient sealing from completely filling the concave flexible stopper side altogether in any of the embodiments of the invention.
In any of the gasket embodiments according to the present invention, the inner sealing portion can optionally be longitudinally offset in various configurations, such as a generally “Z-shaped” half-embossment or a inclined or angled partially embossed or bent configuration, for example, as will become readily apparent to those skilled in the art from the drawings and from the following description and claims. Additionally, the inner sealing portion of the carrier, instead of being integrally formed by bending or by embossing as part of the carrier, can optionally be substantially separated from the remainder of the carrier member but interconnected and held in place by two or more connecting struts or by one or more “living hinges” formed of the resilient sealing material. Such living hinge or hinges can be between any pair of, or any combination of, the inner sealing portion, the intermediate carrier portion and/or the flexible stopper. Two or more flexible stoppers can also be optionally included in some or all of the embodiments of the invention, with such multiple flexible stoppers facing in opposite longitudinal directions, facing in the same longitudinal direction, or any combination of such orientations.
It should further be noted that gaskets according to the present invention can be advantageously used in a wide variety of applications, such as cylinder head and block sealing for internal combustion engines, gas compressors, or other devices having a sealed cylinder containing liquid or gaseous fluids, sealing intake, exhaust or other fluid conveying manifold applications, sealing between piping flanges, or sealingly isolating the interior from the exterior of housings or enclosures, for example. The present invention provides special advantages where relative movement can occur between the members being sealed, such as that due to thermal, mechanical or fluid conditions or environments presented by a particular applications. Those skilled in the art will undoubtedly recognize many other advantageous applications of gaskets according to the present invention.
In addition, it should be emphasized that in any of the embodiments discussed herein, more than one layer of a gasket according to the present invention can be used if desired or needed in various applications. Such applications include those where additional thickness is needed to match the thickness of a previous gasket or gasket assembly that is being replaced by a gasket assembly according to the present invention, or where particular (e.g., increased) spring rate, loading and/or deflection characteristics are desired or needed in conjunction with the flexible stopper characteristics and features discussed herein.
Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.